Re: Positive Newborn Screen for Isovaleric Acidaemia (IVA)

Dear Doctor,

Re: Positive Newborn Screen for Isovaleric Acidaemia (IVA)

[name of child] has been detected on newborn screening to have a positive test for Isovaleric Acidaemia (IVA). This is a rare inherited block in the breakdown of the amino acid leucine. Children with this condition are at risk of encephalopathy, coma and death resulting from the accumulation of isovaleric acid, which is toxic at high concentrations. However, this can be effectively managed in the longer term with dietary therapy and the medications carnitine and / or glycine.

A mild variant of IVA (the 932C>T variant) exists which is not associated with severe encephalopathy and has a very good outcome. The only treatment needed is an emergency regimen at the time of any intercurrent illness.

The positive test so far is a screening test, and therefore it is essential for the Specialist Metabolic Team to urgently review [name of child] to confirm the diagnosis and start treatment. The team will meet with the family to further explain the condition. [name of child] will be specifically tested for this variant.

Definitive testing for IVA involves acylcarnitine and genetic testing from a blood sample and organic acid testing from a urine sample.

Infants may already be symptomatic prior to this screening test result being known. Symptoms may be subtle including poor feeding or excessive sleepiness. Vomiting is common. If [name of child] is already an inpatient, transfer will be organised to the local Specialist Metabolic Centre at [name of IMD Centre] for further assessment and management. If [name of child]is at home, urgent review at your local Paediatric Centre, [name of local hospital], will be organised today. This is for initial review prior to transfer to [name of IMD Centre]. Early intervention is essential for best outcomes.

If [name of child] is well, definitive testing will be arranged, and the results will be available a week later. [name of child] will then be reviewed within a week and in the meantime will be given an emergency regimen and advice to attend hospital if unwell or contact the specialist team if there are feeding difficulties. If [name of child] is unwell, admission to the [name of IMD Centre] will be arranged and definitive testing performed and treatment commenced. Treatment will include a low protein diet with a supplement and carnitine and / of glycine, and an emergency regimen will be provided on discharge.

If the parents would like to discuss any matters prior to this review, [name of clinician] may be contacted on [contact number].

The long-term prognosis is dependent on the initial presentation and degree of encephalopathy and how quickly this can be reversed. Immunisations should be undertaken as normal, and general care is unaltered. The condition is inherited in an autosomal recessive fashion, with a 1 in 4 risk of recurrence in each pregnancy.

You will be or may have already been contacted by [name of clinician] to discuss contact with the family. If you have any further questions, please do not hesitate to contact [name of clinician]. A further letter will be sent to you following review by the Specialist Metabolic Team.

Guidance for the emergency treatment of IVA is available in the emergency guidelines section of the BIMDG website:

Further information can be found about the Expanded Newborn Screening pilot at

With kind regards

Yours sincerely

Enc:Metabolic Team contact details

Emergency regimen

IVA is suspected leaflet

GP Letter: IVA suspected Version 1.0 dated 18/07/12